Housing, management and environment during farrowing and early lactation - The Gestating and Lactating Sow - page 224

10.5.3 Housing and its effect on duration of farrowing and piglet mortality

There appears to be a clear connection between housing and piglet mortality as they
both relate to farrowing duration (Table 10.1). Many studies found that housing in crates
prolongs farrowing by 90 min on average, with crated sows having farrowings that last
over 300 min. Similarly, a farrowing duration of over 300 min was associated with a
higher stillborn rate compared with farrowings lasting less than 200 min (Gu et al. , 2011;
Oliviero et al. , 2008a, 2010).

The association between longer duration of farrowing and the greater incidence of
stillborn piglets is even stronger without considering the housing. Sows with a duration
of farrowing longer than 300 min had 1.4±1.5 (mean ± SD) stillborn piglets, whereas
sows with a duration of farrowing shorter than 300 min had 0.5±0.9 stillborn piglets
(Oliviero et al. , 2008a). The longer duration of farrowing for sows housed in farrowing
crates instead of pens may be connected to the crate itself and to the absence of an
adequate substrate for nest-building. Both these factors may interfere with the natural
expression of the sow's nest-building behaviour, thereby increasing the sow's level of
stress at farrowing (Lawrence et al. , 1994; hodberg et al. , 1999). As previously discussed,
the high concentrations of circulating cortisol present during farrowing demonstrate
that parturition in itself triggers a stress-mediated response in the sow. This interaction
between the environment and the sow's physiology may also have an influence on the
sow's health status, in a domino effect whereby the environment affects the nest-building
behaviour and, consequently, the duration of farrowing, which may impact the sow's
health. There is evidence that sows with a farrowing duration of ≥4 h are at a high risk
of having fever at on the first day after parturition compared with sows with duration of
farrowing <4 h (Tummaruk and Sang-Gassanee, 2013).

10.6 Duration of farrowing and influence on sow fertility

The complex interaction between the environmental effects on the physiology of sows
at farrowing seems to extend even further to the subsequent fertility of the sow. Recent
findings demonstrate that sows with long duration of farrowing (>300 min) have a higher
repeat breeding rate (Figure 10.3; Oliviero et al. , 2013). This finding can provide valuable
information for sow reproductive management. There is no clear explanation yet for this
interaction. In free-ranging domestic pigs kept in a semi-natural environment, weaning
of the litter is a slow and gradual process, taking between 91 and 126 days post-partum
(Jensen and Recén, 1989). On the contrary, in commercial piggeries the lactation period

Table 10.1. Number of stillborn piglets according to housing type (Gu et al., 2011; Oliviero et al ., 2008a, 2010).

Housing Number of stillborn Average duration of farrowing (min) Litters

Pen 0.6±0.8 208±58 89

Crate 1.1±1.1 297±130 133